Burner-lance

ABSTRACT

THE INVENTION PROPOSES A BURNER-LANCE COMPRISING IN A COOLING JACKET A BURNER INSERTION INCLUDING CONDUITS FOR LIQUID FUEL AND A FLUSH GAS SUCH AS COMPRESSED AIR, A CONTROL BLOCK AT THE MOUTH END OF THE LANCE FOR SELECTIVELY CONNECTING SAID CONDUITS TO THE NOZZLE OUTLET, AND A STEAM PIPE SURROUNDING SIAD CONDUITS TO KEEP THE SYSTEM WARM, AN ANNULAR CANAL FOR THE SUPPLY OF THE OXYGEN CONTAINING GAS BEING FORMED BETWEEN SAID BURNER INSERTION AND SAID COOLING JACKET. THIS BURNER-LANCE IS DESTINED FOR HEATING OR MELTING DOWN A SOLID METAL CHARGE AND WHEN PURE OXYGEN IS USED IT IS PARTICULARLY WELL SUITED FOR REFINING. THE BURNER-LANCE ACCORDING TO THE INVENTION MEETS HIGH SAFETY STANDARDS. OPERATION IS READILY STARTED AND TERMINATED AND CHOKING OF THE NOZZLE PARTS IS AVOIDED.

United States Patent O 3,606,292 BURNER-LANCE Meinhard Truppe, Hellmuth Smejkal, Matthias Schemthaner, Gnter Poferl, and Johann Hartl, Linz, Austria, assignors to Vereinigte Osterreichische Eisenund Stahlwerke Aktiengesellschaft, Linz, Austria Filed Apr. 9, 1970, Ser. No. 26,897 Claims priority, application Austria, Apr. 18, 1969, A 3,755/ 69 Int. Cl. C21c 7/00 U.S. Cl. 266-34L 10 Claims ABSTRACT F THE DISCLOSURE The invention proposes a burner-lance comprising in a cooling jacket a burner insertion including conduits for liquid fuel and a ush gas such as compressed air, a control block at the mouth end of the lance for selectively connecting said conduits to the nozzle outlet, and a steam pipe surrounding said conduits to keep the system warm, an annular canal for the suppply of the oxygen containing gas being formed between said burner insertion and said cooling jacket. This burner-lance is destined for heating or melting down a solid metal charge and when pure oxygen is used it is particularly well suited for refining. The burner-lance according to the invention meets high safety standards. Operation is readily started and terminated and choking of the nozzle parts is avoided.

The invention relates to a burner-lance comprising a burner insertion including conduits for liquid fuel and an oxygen containing gas, in particular pure oxygen, and a cooling jacket consisting of concentrical tubes surrounding said burner insertion.

In such burner-lances the liquid fuel and the oxygen are each separately conveyed through the conduit system of the burner insertion. The fuel and the oxygen may mix only outside the lance in order to avoid explosions. Burner-lances of this kind are used in metallurgical furnaces, particularly in open-hearth-furnaces and basic-oxygen converters for heating or melting down a solid metal charge. Burner-lances are exposed to high mechanical and thermal stresses. With a melt weight of e.g. 300 mt. and a throughput of up to about 500 kg. fuel oil/min. and 1000 Nm.3 1 of pure oxygen/min., these lances may be up to 20 rn. long and up to 500 mm. thick. Burner-lances have to be movable, i.e. displaceable in vertical direction; they have to meet high safety standards. It is necessary to provide for a tube between the supply conduit for the liquid fuel and the supply conduit for the oxygen so that in case the fuel conduit leaks an immediate mixture between oxygen and fuel is prevented and the danger of an explosion is eliminated. Since burner-lances as a rule are only intermittently in operation it is a further requirement that they may quickly be made ready for operation and stopped. All constructions of burner-lances known so far have the disadvantage that prior to using the lance the fuel oil has to be pre-heated and it takes several minutes until the burner ignites because it is a rather long path from the slide valves via the hoses to the lance and through the conduits of the lance itself. The same disadvantage makes itself noticeable when the conduits of the lance are shut ot because of an undesired long running of the fuel oil. These side effects lead to black smoke clouds and the production has to be interrupted. The nozzle parts of burners operated with fuel oil tend to choke and crack; thus provisions have to be made for blowing through the nozzle parts and conduits during operation intervals which, however, is rather diicult and time-con- 1 'One N111.3 is a nu.3 taken invby gas at 0 C. and atmospheric pressure (760 mm. Hg).

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suming with burner-lances known so far. Furthermore safe measures have to be taken that also in cases of operation disturbances-eg, when the current supply breaks down-the oil supply is automtaically closed, i.e. the outflow of oil from the nozzle is automatically interrupted.

The burner-lances used so far have not fulfilled these demands. It has been attempted to meet such requirements e.g. by building in a ball valve in the oil conduit in the area of the nozzle mouth; however, this measure has proved to be absolutely unsatisfactory both with fuel oil and with non-viscous fuel because it is impossible to achieve a tight sealing. The residues and impurities contained in the oil are deposited at the ball body and valve seat so that the burner lance repeatedly has to be dismantled and cleaned.

The invention is aimed at avoiding these disadvantages and difiiculties by creating a burner-lance which meets high safety standards for liquid fuel, particularly fuel oil, and oxygen-containing gas, particularly pure oxygen, in which the fuel and the Oxygen are each conveyed separately to the nozzle mouth, mixed outside the burnerlance and burnt.

This aim is achieved with a burner-lance of the kind described in the introduction in that the burner insertion is provided with a control block in the vicinity of the mouth of the lance for reversibly connecting the conduits of the burner insertion, and in that all conduits of the burner insertion are surrounded by a steam pipe, an annular canal for the supply of oxygen containing gas being formed between the burner insertion and the cooling jacket.

According to a suitable embodiment the control block is provided with at least one reversing slide for liquid fuels and a flush gas, e.g. compressed air, and with a plurality of bores for liquid fuels, ush gas, oxygen containing gas, in particular pure oxygen, and cooling water.

The reversing slide may be operated pneumatically or hydraulically.

Preferably, the slide piston is provided with a throttle bore through which the control medium may escape in cases of operation disturbances so that the readjusting spring will move the slide piston and automatically close the fuel supply.

According to a preferred embodiment of the invention a reflux conduit for steam and condensed water is provided Within the heated steam tube, the bottom end of said reiiux conduit reaching into a closed bore arranged within the control block. By means of this reflux conduit the condensed water is continuously drained olf. Thus the upper part of the control block is in Contact with the steam and is heated by it as are the conduits in the burner insertion.

Suitably, the nozzle part at the mouth of the lance is releasably connected with the control block. This nozzle part may be cooled With water and provided with a separate water supply and drain comprising a 'bafe element.

In order that the invention may be more fully understood two embodiments thereof will now be described with reference to the accompanying drawings, in which FIG. l is a vertical sectional view of the bottom part of the burner-lance according to the invention, FIG. 2 is a horizontal sectional view along the line II-II of FIG. 1, and FIG. 3 is a vertical sectional view along the line III-III of PIG. 2. FIGS. 4, '5 and 6 are analogous representations of another embodiment; FIG. 5 is a horizontal sectional view along the line V--V of FIG. 4, and FIG. `6 is a vertical sectional view along the line VI-VI of FIG. 5.

The burner insertion 1 (FIG. l) or 1' (FIG. 4) is surrounded by a cooling jacket 2 (or 2') and releasably connected with it by means of bayonet locks 40. An annular canal 8 for the supply of oxygen is formed between the burner insertion and the cooling jacket.

The cooling jacket 2 (2') comprises the inner water tube 4, the outer water tube 5 which tubes are connected with each other by the nozzle tip 3 (or 3'), and an intermediate water tube `6 with a baffle element 7 for guiding the water.

The burner insertion 1 (1') comprises a steam tube 9 which is rigidly connected at its bottom end with a control block or control valve 10 (10') and a number of conduits. A reversing slide 11 is provided in the control block 10 (10') which slide connects the conduits for fuel oil and a ush medium, e.g. compressed air or steam. The slide piston 12 is urged downward by compressed air or compressed water impinging from above and is moved into the starting position shown in FIG. 1 by means of a pre-stressed readjusting spring after the pressure is compensated, i.e. the conduit 27 :for the supply of the control medium is relieved of pressure. The slide piston 12 is provided with three sealing faces 13, 14, 15 which co-act with the slide housing 16. The slide housing is connected with the cylinder 17 which is provided with a screwing 18 having a bore 19 for the supply of the control medium. A throttle bore 21 is provided at the bottom end of the slide piston 12 through which throttle bore in case of disturbances-eg. when owing to a break down of the current supply the electromagnetic valves for relieving the control medium conduit 27 cannot be operated-the control medium may escape via the bore 29 (FIG. 3) and the relief conduit 28 so that the readjusting spring 20 will actuate the slide piston 12, and the fuel outlet be automatically closed.

Within the tube 9 through which heating steam is conveyed until the surface of the control block 10 (10') for keeping warm the oil supply conduit 22 and the reversing slide 11 there are arranged and connected with the control block 10 (10') conduits 25 for the supply of flush air or Hush steam, conduits 32, 33 for the supply of cooling 'water to the nozzle part 36 and a steam reflux conduit 301 for steam and condensed water. The bottom end of the conduit 30 reaches into the closed bore 31 so that the condensed water may continuously be drawn off and a good heat transfer is maintained in the area of the control block 10i (10').

Bores 23 for the oil supply, bores 24 (24') for the oil or ush medium outlet, bores 26 for the supply of the flush medium and bores 34, 35 for the water supply and drain are arranged in the control block 10 (10'), said bores corresponding to the conduits mentioned above. Nozzle part 36 is screwed into the bottom end of the control block 10 which nozzle part is provided with guiding surfaces 38 and an exit opening 37 for oil or flush medium, respectively. Together with the nozzle tip 3 the nozzle part 36 forms an annular outlet canal 47 for the oxygen, the flow direction of which is indicated in FIGS. 1 and 4 by arrows. In the embodiment according to FIG. 1 the nozzle part 36 is water-cooled; the ba'le element for the cooling water is designated by numeral 39. In the embodiment according to FIG. 4 two nozzle parts 43, 44 are provided between which an annular outlet canal 46 for oil or the ush medium, respectively, is provided. In this nozzle the oxygen leaves from the outer annular canal 8 through slits 45 whose axes cross with the axis of the burner-lance, and from the inner bore 42; thus the oxygen is guided in two separate conduits to the nozzle tip 3'. The supply conduit for the oxygen leaving from the center is designated with numeral 41.

Obviously, further embodiments are feasible. Thus, e.g. also the nozzle parts 43 and/or 44 (FIG. 4) may, on principle, be water cooled and also for the nozzle 4 according to FIG. 1 an internal oxygen supply may bc provided.

During operation intervals the slide piston 12 has the starting position shown in FIG. l, i.e. the oil supply through the bore 23 is interrupted owing to the sealing faces 13, 14, and the flush medium may leave the bore 26 (FIG. 3) between the sealing faces 14, 15 into the canal 24, and, via the guiding surfaces 38, and the opening 37, into the open.

When in operation the slide piston 12 is moved downwards into the position shown in FIG. 4 by the control medium supplied through the conduit 27, the oil flows from canal 23 into the canal 24 (or 24'), respectively, and the flush medium supply conduit is closed. At the same time a small amount of the control medium ows Out through the throttle bore 21, the bore 29 and the relief conduit 28. If, during reversing, the pressure above the slide piston 12 cannot immediately be compensated, i.e. the readjusting spring 20 cannot move the slide piston 12, the pressure is reduced owing to the escape of the control medium through the throttle bore 21 so that the slide piston 12 is moved by the spring 20 into the starting position and the fuel supply is automatically interrupted.

The burner-lance according to the invention has proved to be highly satisfactory for heating and melting down solid charges in basic-oxygen converters. There are no delays when the oil supply is started or terminated, the nozzle parts do not incrustate and there are no fume puffs or explosions owing to after-running oil.

Burner-lances according to FIG. 4 are particularly Well suited for melting and rening a metallic charge.

What we claim is:

1. A burner-lance comprising a burner insertion dening a number of conduits including ducts for directing liquid fuel and an oxygen containing gas to a nozzle mouth formed on one end of said burner-lance, and a cooling jacket composed of concentrical tubes surrounding said burner insertion, and further comprising a control block in said burner insertion near the mouth end of the burner-lance for reversi-bly connecting individual conduits of said burner insertion, and a steam pipe surrounding all conduits of said burner insertion, an annular canal for the supply of the oxygen containing gas being formed between said burner insertion and said cooling jacket.

2. The burner-lance set forth in claim 1, wherein the oxygen containing gas is pure oxygen.

3. A burner-lance comprising an outer jacket composed of concentrical tubes and having connections for circulation of a coolant therethrough, a burner insertion arranged coaxially within said jacket and comprising a set of conduits for operating media including a liquid fuel and a flush gas; a steam pipe enclosing said set of conduits; and a nozzle portion having at least one outlet for at least one of said operating media, an annular duct for the supply of oxygen-containing gas between said burner insertion and said outer jacket, and a control block interposed between said set of conduits and said nozzle portion, said control block comprising a number of bores for said operating media and at least one reversing slide operable to selectively connect said conduits for liquid fuel and flush gas to said outlet.

4. The burner-lance set forth in claim 3, wherein said burner insertion includes a conduit and nozzle outlet for an oxygen containing gas.

5. The burner-lance set forth in claim 3, wherein said reversing slide is pneumatically operated.

6. The burner-lance set forth in claim 3, wherein said reversing slide is hydraulically operated.

7. The burner-lance set forth in claim 3, wherein said reversing slide comprises a piston operable by a pressure fluid against the action of a pre-stressed readjusting spring, said piston comprising a throttle bore for draining said pressure fluid in case of operational disturbances so that said spring will urge said piston to a position wherein the fuel supply is closed.

8. The burner-lance set forth in claim 3, wherein a. reflux conduit for steam and condensed water is provided within said steam pipe, the bottom end of said reux conduit reaching into a closed bore arranged in said control block.

9. The burner-lance set forth in claim 3, wherein said nozzle portion comprises at least one part releasably attached to said control block.

10. The bumer-lance set forth in claim 3, wherein said burner insertion includes conduits for supplying and draining coolant water to and from circulation means in said nozzle portion.

References Cited UNITED STATES PATENTS 2,937,864 5/1'960 Kcsterton 266-34L 3,045,997 7/1962 Hudson 266-34L 3,169,161 2/1965 Kurginski 266-34L 10 GERALD A. DOST, Primary Examiner U.S. C1. X.R. Z39-132.3 

